Off-highway trucks equipped with rear eject bodies are used to haul and dump materials in haulage applications such as mines, construction sites and landfills. Rear eject bodies have a number of advantages over conventional rear dump bodies. For example, rear eject bodies typically are self-cleaning thereby minimizing carry back of sticky materials. Additionally, this style of body allows dumping on the go, increasing truck productivity. Dumping on the go also minimizes the need for additional support equipment to spread and level the dumped material. With regard to the dumping of materials, rear eject bodies allow materials to be dumped on steeper slopes and in areas where there is soft truck underfoot conditions. Moreover, trucks with rear eject bodies can dump their loads in areas with overhead wires and bridges as well as in tunneling applications.
In contrast to conventional rear dump bodies which are pivoted into a raised position for dumping, rear eject bodies use an ejector blade that is moved horizontally from the front end to the rear end of the truck body by one or more hydraulic cylinders to eject and dump material from the truck body. Since the body does not have to be raised for dumping, rear eject bodies are particularly suited for haulage applications in which there is limited overhead dump clearance (e.g., because of wires, bridges, tunnels, and trees), underground haulage application or haulage application where ground instability makes raising a dump body to the dumping position extremely hazardous. Additionally, rear eject bodies dump materials in a more controlled manner. For example, a rear eject body can dump material while the truck is still moving in order to spread the dumped material over a larger area. Dumping material while the truck is on the go also speeds the dumping process. The use of the ejector blade also enables rear eject bodies to handle hard-to-dump sticky materials such as dirt and clay mixtures which hang-up and often do not flow out of conventional raised rear dump bodies.
In general, rear eject bodies are well known on both off-highway trucks and street legal refuse trucks. Unfortunately, many commercially available rear eject bodies have a number of drawbacks. For example, since typical rear eject bodies have a number of moving parts requiring regular lubrication and maintenance, they can be costly and time-consuming to maintain. Moreover, because large hydraulic cylinders are required to move the ejector blade, rear eject bodies can be quite expensive. Some rear eject bodies also use additional hydraulic cylinders to operate the tailgate, further increasing the cost. Many rear eject bodies also dump material relatively slowly, increasing dump cycle times and lowering productivity.